In an image forming apparatus such as a printer, a latent image is formed on a photosensitive drum, as the image bearing member which has been uniformly charged, by effecting selective light exposure and the latent image is visualized with toner as the developer to form a toner image, and then the toner image is transferred onto a recording material to effect image recording. After the toner image is transferred, a surface of the photosensitive drum is cleaned by the cleaning member and prepared for subsequent image formation. As a cleaning means for cleaning the photosensitive drum surface, a cleaning device for cleaning the photosensitive drum surface by bringing an elastic blade consisting of a rubber or the like as the cleaning member into contact with the photosensitive drum surface has been known (e.g., Japanese Laid-Open Patent Application (JP-A) 2005-164774). As the developer, in recent years, the toner which has been downsized and/or sphered in order to realize high definition and high quality is used.
With respect to setting during mounting of the cleaning member in the cleaning device, the cleaning member is disposed so as to assume a phantom straight shape of the photosensitive drum in an unloaded condition free from the photosensitive drum to obtain a desired contact pressure. However, particularly in the case where the above-described toner which has been downsized and sphered is used, the toner is liable to pass through the cleaning member and therefore a problem that a setting image in which the cleaning is satisfactorily performed is narrow, occurs. As a result, part accuracy is required and thus an improvement is desired.